Application of Knorr Reaction in the Synthsis of certain Pyrrole Derivatives which are Structurally Related to certain Pharmacologically active compounds

A survey covering the synthesis of pyrrole com¬pounds via the Hantzsch, Paal-Knorr and Knorr syntheses is given.A brief outline on the medicinal importance of pyrrole derivatives, carboxamides, N-acyl derivatives and chalcones as well as the effect of methyl and ethoxy-carbonyl groupings on biological activity is mentionedThe different methods of preparing the intermediates are thoroughly investigated and the experimental results attained are critically discussed.Moreover, some of the new compounds were subjected to preliminary pharmacological screening and the results attained are summarized.The present investigation involves the preparation of the following unavailable starting materials and intermediates:1 ) 2, 4-Dicarbethoxy-3 , 5-dirne thylpyrrole .2) 2-Carbethoxy-3 , 5-dirnethylpyrrole-^i-carboxylic acid.3) 2-Carbethoxy-3 , 5-dimethylpyrrole-^i-carbonyl chloride. ’() ^-Carbethoxy-3,5-dimethylpyrrole-2-carboxylic acid.5) 2,4-Dicarbethoxy-1,3,5-trimethylpyrrole.6) 2-Carbethoxy-1,3,5-trimethylpyrrole-4-carboxylic acid.7) 2-Carbethoxy-^-acetyl-3,5-dimethylpyrrole.